For many drugs and treatment needs respiratory drug delivery represents an attractive or unique solution. Delivery of drugs by inhalation, however, is often challenging for a number of reasons. Especially for solid drugs, one challenge is often the design of an appropriate system used for drug delivery. Powdered drugs generally need to be aerosolized before inhalation, a process often requiring systems with high operation reliability and reproducibility for consistent and effective drug delivery.
Several respiratory drug delivery systems have been employed, but they usually have one or more undesirable features. Some delivery systems are bulky, making their transportation inconvenient and thus potentially compromising treatment compliance. Some delivery systems are very expensive to produce, making their adoption unlikely even for routine use for chronic conditions. Some devices contain a pump to pressurize air, which could require a large number of parts and moving parts, with the associated high cost of production, expected wear and tear, as well as challenges for young or old users, or patients suffering from conditions such as clubbed fingers. Inconsistency of the delivered dose is a common shortcoming of present delivery devices, as might be the need of forceful inspiratory flow rate. Time dependent dose variability is most often due to either device reliability (wear and tear) or, for some devices, progressive decrease of drug canister pressure. Furthermore, the percentage of the aerosolized drug that reaches the lung for deposition is often variable, and some systems cannot be easily scaled for child or adult use.
Accordingly, there is a need for improved respiratory drug delivery devices and methods. Ideally, new devices should be compact for portability and to ensure good treatment compliance by patients. Devices should also be inexpensive to the point where they are disposable or routinely replaceable, or contain disposable parts that ensure inexpensive long-term operation. Respiratory drug delivery systems should be easy to use by any group of patients, and should reproducibly generate the required dose of aerosolized drug. Operation of drug delivery devices should not require forceful inspiration. Furthermore, devices are needed that are easily adaptable for the needs of adult or pediatric patients.